I feel like this should be incredibly obvious, yet it needs to be stated.
This is a world where money and those who have it control politics.
Anyone who tries to go against it gets undermined and suppressed.
In the United States 2016 election, there was Sanders, who supported a nicer version of capitalism, free healthcare, etc. The DNC rigged him out, so we got Clinton vs Trump. Of course neither candidate would do literally anything to get rid of our current plutocracy. The supposed “left-wing” candidate Obama didn’t do much either after all. Either way, Trump won. And that’s why we have what we have right now.
In the UK, Corbyn was a similar left-wing candidate. However, his own party undermined him, calling him antisemitic (for opposing the Israeli genocide in Gaza). His party lost. Nowadays, the UK has bad and unpopular prime ministers.
In France, the same thing happened with Mélenchon.
Then in the US it happened again. Sanders ran again and was even 1st place in the primary, but democrats rallied around Biden (3rd place) and got all of the other candidates to drop out. Biden still won the elections against Trump, but just barely. As president he did absolutely nothing to improve the current system. Either way, 4 years later they didn’t even allow a primary, and Trump won (see recent events). Trump is a billionaire, and I don’t think I have to say why billionaires don’t care about the poor.
And the people I mentioned in the post aren’t even that left. They’re social democrats. But all of these supposedly “left” parties would rather have a government controlled by an evil far-right billionaire rather than anyone who could in any way even try to undermine the power of the capital.